Stencil duplicating machines



Jam 22, 19.57 T. G. HowE 2,778,299

STENCIL DUPLICATING MACHINES Filed Dec. 14, 1953 4 sheeis-sheet 1FTOIQ/VEY Jan. 22, 1957 T. G. HowE 2,778,299

STENCIL DUPLICATING MACHINES I Filed Dec. 14, 1953 4 Sheets-Sheet 2 Jam22, 1957 T. G. Howl- 2,778,299

STENCIL DUPLICATING MACHINES Fled Deo. 14, 195s 4 sheets-sheet' 5INVIA/TOR Tfno/m5 ifa/@G5 Hou/6 ATTORNEY Jan., 22, 1957 T. G. HowE y2,778,299

STENCIL DUPLICATING MACHINES Filed Dec. 14, 1953 4 Sheets-Sheet 4nvenlor 740/745 G. HOWE BWZ A Horn e y Unit STENCIL DUPLICATING MACHINESApplication December 14, 1953, Serial No. 398,164

6 Claims. (Cl. 1111-118) In stencil duplicating machines, such as foroflice use, there is provided a pressure roller movable towards and awayfrom the cylinder of the machine in synchronism with the paper feedwhereby when `a sheet is advanced for duplicating the roller is raisedto press the sheet 4against the stencil which is wrapped round thecylinder. The pressure roller is actuated from the driving motor orhandle, being raised and lowered as each sheet is fed through themachine. The pressure roller is actuated by a clutch mechanismcontrolled by a paper detector so that if a sheet of paper is not fedforward the roller is not raised as otherwise the roller would engagethe stencil and be coated with ink which is clearly undesirable. Withincrease in the speed of operation of the machine there is a tendency,beyond a certain speed of operation, for the paper detector and theclutch mecha- -nism (which is canil operated) not to be accuratelycontrolled by the cam and consequently for vibrationto be set up in themachine. Additionally there is the possibility that the detector maypermit the roller to engage with the stencil and become coated with ink.

The present invention aims to provide an improved mechanism forcontrolling the pressure roller by the paper detector.

Another object of the invention is to ensure that the cam movements areaccurately applied to the pressure roller and to the paper detector athigher speeds than those at present prevailing.

The paper detector usually comprises a finger or ngers lowered ybyspring means to engage the top of each sheet of paper after the latterhas been fed forward and the cam follower has been provided to actuatethe paper detector and a clutch throw-out mechanism, said spring meansbeing effective also to -hold the cam follower against the cam. Afurther 4object of this invention is the provision of separate springmeans for the paper detector and for the cam follower.

Another object of the invention is to provide that the paper detector becontrolled separately of the cam fcllower so that a light and sensitivedetection of the presence of paper is possible while ensuring that thecam follower is effectively held against the cam at all speeds ofoperation. This and other objects of the invention will be betterunderstood from the following description of a duplicating machine -inaccordance with the present invention. The description which followsisvmade with reference to the accompanying drawings of which:

Figure l is a side view of a stencil duplicating machine illustratingthe paper detector and the pressure roller actuating mechanism, themechanism being shown in the position assumed in the absence of a sheetof parer,

Figure 2 is a view corresponding to Figure l and showing certain partsof the mechanism during detection of the presence of a sheet of paper,

Figure 3 is an end view showing certain details of the mechanism ofFigures l and 2, and

Patent Patented Jan. l22, `1957 Figure 4 is a vi-ew of a mechanism forraising and lowering a pressure roller.

Referring to Figure l: the duplicating machine comprises side frames 5between which are rotatably mounted an upper cylinder 6 and a lowercylinder 7 around which passes a silk screen 8 to which a stencil may beattached in well known manner. The cylinders 6 and 7 are rotated by thehandle 9 (part only of which is shown) which drives gear wheel 10meshing with a pinion 11 carried on the spindle of cylinder 7. Thepressure roller 12 is supported from a shaft 13 carried by brackets (notshown) secured to the frames 5. The shaft 13 is secured to a lever 14which constitutes part of a mechanisrn for raising the roller 12ftoengage a sheet of paper being `fed through the machine, the lever 14being operated, through a pair of cam followers 15, 15', by a cam 16.If'reference be made of Figure 4, it will be noted that the camfollowers 15, 1S are adapted to engage opposite sides of the cam 16 andare secure-d to a carrier plate 7d which is slidably mounted lin guideways 71 projecting from a member 72. ri^he plate 7l? is formed with an.arcuate slot 73 which receives a pin 74 carried by a lever 75. Thelever 7S is p-ivotally supported at 76 and is integral with a secondlever' 7"7. The lever 77 carries a block '7d coupled to the lever 14 byway of a connecting rod 79. Rotation of the cam 16 will therefore slidethe `carrier plate itl to and fro along the guide ways 71, movement ofthe plat-e 7d being transmitted by the levers '75, 77 to the shaft 13and hence to the pressure roller 12 so as to raisc'and lower it. Theshape of the cam 16 and the spacing of the followers 15, 15' is suchthat when the cam is moved through angular positions such that thepressure roller i2 is being raised or is being maintained in contactwith the cylinder '7, thefollowers 15", 1S closely engage opposite sides*of the cam 16. This is illustrated in Figure 4, where the cam 16 isshown in the position corresponding to the position offmaximlum lift ofthe pressure roller. It will be appreciated that this construction,which is more fully described in the speciiicationoi my copendingapplication Serial No. 398,162, ensures that when the cam 15 isv in theposition shown in Figure 4 it accurately and positively controls 'theposition of the plate 71B since its opposite sides are engaged by thefollowers 15, 15 at this time. Rebound of the pressure roller on hittingthe cylinder 7 is therefore prevented.

The earn 16 is driven from a gear wheel 1"/ which meshes with a pinion13 driven by gear 11. Within the gear wheel 17 there is disposed aclutch (Figure 2) comprising Ian arm 19 pivoted at 2i) and having a ciaw21to enter a notch ,22 in the gear wheel 17. 19 is carried on a shaft towhich the cam 16 is attached. A pin 23 projects sideways from the arm 19as more fully shown in Figure 3. the notch 22. When the claw 21 liesWithin the notch 22 gear wheel 17 is driv-ingly connect-edA to the cam15 `and the pressure roller is raised as more fully described in thespecification of depending application Serial No. 398,162. As indicatedby the arrows in Figures l and 2 the clutch assembly rotatesanti-clockwise so that if the pin 23 is brought against an obstructionthe arm 19 is rocked to disengage the claw il from the notch 22 with theconsequence that the drive to the cam 16. is interrupted. Consequentlythe pressure roller 12 will not be raised.

Projecting into the line of path of the pin 23 is a linger 25 of aslider 26 which is carried by the frame of the machine. The slider 26has a cut out 27 to receive a linger 2d forming part of a lever 29pivoted at 30 and carrying a paper detector linger 31 which co-operateswith a plate 32 having holes 3,4 to receive the fingers 31.

The arm A spring 24 urges the claw 21 into' when. a Sllsst of .paper isfel terr/,ard it travels .across the top of the plate 32-such a sheet ofpaper is indicated at 33 in Figure 2. A spring 35 urges fingers 31against the plate :32, and to bring lthe finger -ZSvasaiflSt the face 36of slider 26. The lever 2 9 carries a Vpin 3.7 which surged bvtsprins3,5, asainsttarm 330i 'a lever SQA-pivoted to the -frame at 41,4) andcarrying a ,cam follower 41 to engage thecam 42 which is driven-by means(not shown) from ,the handle 9,. A spring 43 maintains the follower 41-against the cam 4 2.

With the-arrangement so far described the cam i2 acts to swing arm 3 8so that spring 3 5 rocks lever v29 with the nger 28 moving within cutout 2,7. At the same time the fingers 31 of vthe paper detector aremoved towards plate k32. While a sheetojftpaper 33 rests on the plate 32the fingers 3,-1 will .engage with the top of the `sheet ofpapcr and`further movement of the lever v29 (which is permitted by the arm 38) isprevented and the linger 2S stops short of the lface 36. However, itthere is no paper the fingers 31 pass through the holes 34 (see Figurel) and finger 23 is brought against face 36 to move the slider 2,6sothat the-linger 2 5 thereof is brought into the path ofpin 2,3 -with theresult that the clutch is disengaged as described above and the pressureroller 12 is not raised.

A latch 4S is carried at 46 by the slider 26 and is urged by spring 47to engage behind a notch 48 (sec Figure l) of slider 26 when the latteris advanced to discngagc the clutch. When arm 38 is next moved clockwiseit engages pin 37 to move lever 29 anti-clockwise. However, slider 26 isheld against movement by the latch 4S until arm 49 of lever 29engagesepin 50 of latch 4S to raise the latter and to move the slider 26whereby finger 25 is withdrawn from the pin 23. It will be apparenttherefore that when the slider 26 is advanced to disengage the clutch itis heldin this position until another sheet of paper is about to be fedforward.

,lt is a particular advantage of the present invention thatA the spring35 is independent of the spring 43 since it is permitted thereby thatthe spring V43 be readily chosen to v.ensure that the cam follower 41 isheld in engagement with the cam 42, while the spring 4S may bevrelatively light such as will ensure that the iingers 3l etectivelydetect the presence of a sheet of paper on the plate 32 without,however, puncturing the paper and passing into the holes 34. By theprovision of independent ysprings for the paper detector and for the camfollower the spring 43 may he selected to ensure that at all speeds ofoperation the cam follower will be maintained against the cam. f

When the machine is inoperative in the sense that duplication has ceasedalthough the cylinders 6, 7may continue to be driven e. g. a specifiednumber ofcopies has been run oi or for other reasons the paper feedmechanism is automatically rendered inoperative. 'At other times thepaper feed mechanism is rendered inoperative by manual ymeans, forinstance by a linger piece S5 which for this purpose is set `to theposition shown in Figure l. At all times when the paper feed isinoperative it is essential that the clutch comprising parts 21, 22 isprevented from engagement to ensure that the pressure roller cannot beraised. Accordingly it is arranged that the finger piece 5S (or othermechanism actuated when a specified number of copies has been run olf)adjusts an arm 56 carrying a pinr57 which engases, .the .inclined .face,of .a .lever 5;9p.11vo.tedat.6ll and having a claw 61 which embraces apin 62 carried by the slide 26. Y The spring 47 is anchored to the lever59 tending to urge the pin 62 towards the right. When the arm 56 is thusbrought to the position shown in Figure l such movement by spring ,0E-2is permitted with the consequence that the finger 25 of the slide 26 isadvanced to lie in `the ypath .of the pin 23 and thereby `prevent theclutch from being engaged while the paper feed is stopped.

I claim: 4

l. A stencil duplicating machine comprising a frame, a cylinderrotatably mounted in the frame and carrying the stencil, a'pressureroller, a support for the pressure roller whereby the roller is movableAtowards the cylinder to press a sheet of paper against the stencil,means for advancing the pressure roller to engage a sheet of paper fedinto the machine to press it against the stencil, said means-foradvancing thetpressure roller being driven from said cylinder rdrivingmeans, a clutch to interrupt the drive to the means `for advancing saidpressure roller, means Vfor disengaging said clutch, means to detecteach sheet of Ipaper as it is fed forward for duplicating and foractuating said clutch-disengaging means on the absence ofpaper, springmeans urging the detector means into engagement with the paper sheet, acam-follower means for @actuating said clutch-disengaging means and toretract the paper detector from the paper, spring means to maintain thefollower in engagement with the cam and a common means for driving thecylinder, said cam andthe means for advancing the pressure roller.

y 2. A stencil duplicating machine as claimed in claim l whereinthepaper detector comprises a spring-urged lever carrying a'nger toengage the upper surfaceof the sheet of paper whereupon movement of thelever by said spring means is prevented and there is a slide whichactuates the clutch to disconnect the drive to the pressurev roller,absence of paper permitting further movement of the lever whereby afinger of the lever engages said slide to disconnect the drive to thepressure roller.

3. A stencil duplicating machine as claimed in claim 2 in which there isa latch to hold the slide in an advanced position cprresponding with thedrive to the clutch being disconnected.

4. A stencilfduplicating machine as claimed iu claim 2 comprising alever arm against which said lever of the paper detector is held by saidspring means, said lever arm ybeing actuated by said cam mechanism tocontrol movement of the spring-,urged lever of the paper detector.

5. A stencil duplicating machine according to claim 3 whereinmovement ofsaid spring-urged lever in the directionfoppositevto that which resultsin detection of the paper operates `means to .release said latch topermit return of the slide.

6. A ystencilduplicatingl machine as claimed in claim 5 in Whihaspringisconnected to urge the latch to its slide-engaging position and manualselecting means is provided tow-canse said spring to advance the slideto disengage the k-clutch.

References Cited in the tile of this patent UNITED STATES PATENTS884,704 lBrasseur' Apr. 14, 1908 1,237,820 Rogers Aug. 21, i9172,198,728 Horii Apr. 30, 1940 Yi .hpv

